Method for reproducibly determining object characteristics

Abstract

A method for reproducibly determining object characteristics is disclosed. Herein an object is imaged onto a detector by means of an imaging optics and detected thereon. A correction function k is applied to a brightness measuring result N originally detected by a detector in such a way, that a corrected brightness measuring result N′ is proportional to a brightness I impinging on the detector.

Description

[0001]This claims the benefit of German Patent Application No. 10 2007 039 021.3, filed on Aug. 17, 2007 and hereby incorporated by reference herein.[0002]The present invention relates to a method for reproducibly determining object characteristics.BACKGROUND[0003]Methods for the detection of objects of the generic type are already well known from the practice. Object characteristics can be, for example, the width, the position and the brightness of the structure on the object and / or the brightness of the object itself. All the characteristics referred to are ultimately based on the detection of brightness, since the accuracy with which a width and a position of an object is obtained is also determined by the varying brightness or detected brightness.[0004]In industrial applications, such as in the metrology of line widths or positions on substrates in the semiconductor industry, coordinate measuring machines are utilized of the type described, for example, in German Patent Applicat...

AI Technical Summary

Benefits of technology

"The present invention provides a method for correcting non-linearities in measuring results obtained from an object. The method involves applying a correction function to a brightness measuring result obtained from an optical detector. The correction function is determined based on a defined change to the brightness measuring result caused by a positioning of a transmission or reflection filter, an exposure time of the detector, or a calibrated gray filter. The method allows for reproducible determination of object characteristics, such as position, line width, and brightness, regardless of the non-linearities of the detector or the light source. The method is applicable to various types of detectors and can be used in various industrial settings."

Problems solved by technology

In practice, however, the residual error is still relatively large even after error reduction.

Thus all the linear variations of the originally detected brightness measuring results are practically harmless with regard to a possible deformation of the detected image.

On the contrary existent measuring systems, such as the light sensor mentioned above, exhibit non-linearities which are small in the case of a good system, but which cannot be disregarded when a very precise measurement is required.

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